I need help question 13

TiliK225 [7]

Taking into account the definition of dilution:

you have to use 8.23 mL of a stock solution of 7.00 M HNO₃ to prepare 0.120 L of 0.480 M HNO₃.
If you dilute 20.0 mL of the stock solution to a final volume of 0.270 L , the concentration of the diluted solution is 0.518 M.

<h3>Dilution</h3>

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where

Ci: initial concentration
Vi: initial volume
Cf: final concentration
Vf: final volume

<h3>Volume of stock solution</h3>

In this case, you know:

Ci= 7 M
Vi= ?
Cf= 0.480 M
Vf= 0.120 L

Replacing in the definition of dilution:

7 M× Vi= 0.480 M× 0.120 L

Solving:

Vi= (0.480 M× 0.120 L)÷ 7 M

<u><em>Vi= 0.00823 L= 8.23 mL</em></u> (being 1 L= 1000 mL)

Finally, you will need 8.23 mL of the stock solution.

<h3>Concentration of the diluted solution</h3>

In this case, you know:

Ci= 7 M assuming the stock solution is 7.00 M HNO₃
Vi= 20 mL= 0.02 L
Cf= ?
Vf= 0.270 L

Replacing in the definition of dilution:

7 M× 0.02 L= Cf× 0.270 L

Solving:

(7 M× 0.02 L)÷ 0.270 L= Cf

Finally, the concentration is 0.518 M.

Learn more about dilution:

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#SPJ1

5 0

1 year ago

Electromagnetic waves heat earths surface through convection?

larisa86 [58]

Heat moves in three ways:Radiation, conduction, and convection. Radiation happens when heat moves as energy waves, call infrared waves,directly from its source to something else.This is how the heat from the Sun gets to Earth.In fact,all hot things radiate heat to cooler things:).hope this helps

4 0

3 years ago

Which of the following is a farming method that helps reduce the effects of wind erosion?

MrMuchimi

You can reduce wind erosion by providing a protective plant cover for the soil.

4 0

3 years ago

A student makes the following hypothesis: If the amount of chocolate increases then the cake will taste sweeter. What is the ind

Talja [164]

Answer:

the chocolate

Explanation:

You are changing the amount of chocolate

8 0

3 years ago

Copper(II) sulfide is formed when copper and sulfur are heated together. In this reaction,

storchak [24]

Answer:

The mass of copper(II) sulfide formed is:

= 81.24 g

Explanation:

The Balanced chemical equation for this reaction is :

$Cu(s) + S\rightarrow CuS$

given mass= 54 g

Molar mass of Cu = 63.55 g/mol

$Moles = \frac{given\ mass}{Molar\ mass}$

$moles=\frac{54}{63.55}$

Moles of Cu = 0.8497 mol

Given mass = 42 g

Molar mass of S = 32.06 g/mol

$Moles = \frac{given\ mass}{Molar\ mass}$

$moles=\frac{42}{32.06}$

Moles of S = 1.31 mol

Limiting Reagent :<em> The reagent which is present in less amount and consumed in a reactio</em>n

<u><em>First find the limiting reagent :</em></u>

$Cu + S\rightarrow CuS$

1 mol of Cu require = 1 mol of S

0.8497 mol of Cu should require = 1 x 0.8497 mol

= 0.8497 mol of S

S present in the reaction Medium = 1.31 mol

S Required = 0.8497 mol

S is present in excess and <u>Cu is limiting reagent</u>

<u>All Cu is consumed in the reaction</u>

Amount Cu will decide the amount of CuS formed

$Cu + S\rightarrow CuS$

1 mole of Cu gives = 1 mole of Copper sulfide

0.8497 mol of Cu = 1 x 0.8497 mole of Copper sulfide

= 0.8497

Molar mass of CuS = 95.611 g/mol

$Moles = \frac{given\ mass}{Molar\ mass}$

$0.8497 = \frac{given\ mass}{95.611}$

Mass of CuS = 0.8497 x 95.611

= 81.24 g

3 0

3 years ago